Matthew McGowan

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These experiments examined the extent to which chronic intrahypothalamic (IH) insulin infusions that alter circadian patterns of food intake (FI) affect the regulation of other diurnally varying behavior in the rat. One-week IH insulin infusion (1.5 microU/hr) significantly decreases rats' night FI and increases day FI but does not alter the diurnal pattern(More)
Neurons of the nucleus raphe magnus (NRM) and adjacent nucleus reticularis gigantocellularis pars alpha (NGCp alpha) receive a tonic inhibitory input from gamma-aminobutyric acid (GABA)-ergic neurons that is mediated by GABAA receptors. However, comparatively little is known about the role of GABAB receptors in these nuclei. The present study examined the(More)
This study examined the sites in the central nervous system at which subcutaneously-administered R(+)-baclofen hydrochloride (baclofen), the most active isomer of this prototypic gamma-aminobutyric acid (GABA)B receptor agonist, acts to produce antinociception in the rat. To determine whether baclofen acts in the spinal cord, either saline or the GABAB(More)
In Experiment 1, one-week infusion of insulin (0.15, 1.5, or 15.0 microU/hr) into the ventromedial hypothalamus (VMH) of rats reduced body weight (BW) and nighttime food intake (FI). While 0.15 microU/h decreased daytime FI, 1.5 microU/h increased daytime FI and 15.0 microU/h left daytime FI unchanged. Total daily FI was decreased by the two highest doses.(More)
This study examines whether chronic intrahypothalamic (IH) insulin infusions suppress body weight and food intake directly or via effects on water intake or activity. Insulin (15 microU/h) was infused into the ventromedial hypothalamic nucleus of rats for 1 week. If IH insulin infusions primarily suppress water intake, animals should consume less water(More)
This study examined whether the antinociception produced by glutaminergic stimulation of neurons in the nucleus raphe magnus (NRM) and nucleus reticularis gigantocellularis pars alpha (NGCp alpha) is mediated by an action of GABA at GABAB receptors in the spinal cord. Rats were pretreated with intrathecal (i.t.) administration of the selective GABAB(More)
In Experiment 1, rats were chronically infused with insulin (2.7, 27, or 270 ng/hr) or 0.9% saline into the ventromedial (VMH), medial perifornical (PF), or lateral (LH) hypothalamus. VMH infusions of insulin caused a significant, dose-dependent decrease in food intake and body weight; PF infusion of insulin was less effective, but significant; whereas LH(More)
A randomized controlled field trial was conducted to evaluate the effects of two sets of treatment strategies on ceftiofur and tetracycline resistance in feedlot cattle. The strategies consisted of ceftiofur crystalline-free acid (CCFA) administered to either one or all of the steers within a pen, followed by feeding or not feeding a therapeutic dose of(More)
This study examined whether the antinociception produced by glutamatergic stimulation of neurons in the nucleus raphe magnus (NRM) or nucleus reticularis gigantocellularis pars alpha (NGCp alpha) is mediated by activation of GABAA receptors in the spinal cord. Two approaches were used. The first approach determined the ability of intrathecally (i.t.)(More)
We depleted neurons from the lateral preoptic region (LPO) of rats by iontophoretic application of the neurotoxin kainic acid (KA). Rats with KA-induced damage to LPO neurons drank less water than controls after subcutaneous (SC) administration of: (a) 5 ml of a 1.0 M saline solution or (b) 5 ml of a 30% polyethylene glycol (PG) solution. The drinking(More)